Oh tidings of despond and woe! Thomas Cook shuts hundreds of its travel shops. Philip Green wonders whether hundreds more from his Arcadia empire face nemesis. And it's Christmas bonanza time along the high streets of Britain, where Oxfam outlets and estate agents lie lonely amid empty sites and desolate closed doors. A nation of shopkeepers? Not if you stray far from the hedge fund heaven that is WC1. But victims of the credit calamity? That's only half of the story: the non-digital half.

De Kare-Silver knows retailing. He's sat on the main boards of giant retail chains. He feels the wind of change. He quotes the great guru Richard Hyman of Verdict Research: "Almost every retailer you can think of has got too many shops … and this sentiment is bound to grow as more and more revenue comes through their websites". He knows that so many expansion plans – like those of our grocery giants to open 25m more square feet of new space by 2015 – simply don't add up any longer. To make such investment worthwhile you need £20bn in incremental sales – but the economy is flat going on flat on its back, and digital business is now taking a full 17% of the cake.

Look at the bottom line of most high street retailers, de Kare-Silver warns, and you will see that a 15% drop in store sales pushes them below break even and into loss. In short, this is "gradually ceasing to be a bricks and mortar world". It isn't just the minnows at the wrong end of the high street who are now on the wrong end of history. It's the big fish in the middle who are feeling the pinch. They can't be in digital denial any longer.

But it's here that commercial survival planning and human survival planning start to head in different directions. You can agree, for instance, that turning stores into showrooms merely to sample what's available online may be one way out. You can follow the likes of Dixons, with its 25 megastores. But you can't quite see how human beings are supposed to make sense of their everyday lives in showcase Britain.

At its root, shopping serves one crucial purpose: it defines communities. Your local shops are where you bump into friends, nip out to buy a toaster or pair of shoes, break up the routine of the day – a routine that is growing ever more tenuous as people spend their lives in front of a screen, stuck inside little office boxes or, increasingly, working from home. What happens when the shops die? Neighbourhoods lose reference points. Areas lose their identities. There's no throb of life to the place where you live. It becomes blank, anonymous, savourless.

We've glimpsed some of that through the last 20 years, of course, as supermarkets have killed off butchers, bakers and fishmongers. We've seen the focal points drift on to ring roads where Asda and all the rest can buy, build and sell cheap. But now beware: there's a new kind of threat. That threat is stagnation out of town, and degradation in town. The vans I see day after day – busy delivering vegetables next door, groceries across the road, bringing books, clothes and fridges at the push of a button – are not lifelines but the harbingers of a colder, more lonesome world. Heaven bless social networking, up to a point. But not in a world where only the postman rings twice.